Fuel-based injection control

Abstract

Systems and methods of operating an engine, the engine including an injector configured to directly inject fuel into an engine cylinder. One example method comprises, during an engine cold start, performing compression direct fuel injection, and retarding a timing of the compression injection as a fuel alcohol content of the fuel increases.

Description

FIELD[0001]The present application relates to methods and systems for controlling the injection timing of fuel in an internal combustion engine operating with fuel of varying composition.BACKGROUND AND SUMMARY[0002]Alternate fuels have been developed to mitigate the rising prices of conventional fuels and for reducing production of regulated emissions, such as CO2. For example, alcohol and alcohol-based fuel blends have been recognized as attractive alternative fuels, in particular for automotive applications. Various engine systems may be used with alcohol fuels, utilizing various engine technologies such as turbo-chargers, super-chargers, etc. Further, various approaches may be used to control such alcohol-fuelled engines, including adjustment of boost or spark timing in dependence upon an alcohol content of the engine fuel, and various other engine operating conditions.[0003]One example approach to control alcohol-fuelled engines is described by Brehob in U.S. Pat. No. 7,287,509....

AI Technical Summary

Benefits of technology

This approach improves fuel evaporation and combustion stability at cold-start conditions, enhancing engine startability, fuel economy, and reducing cold-start exhaust emissions without the need for pilot fuel injections.

Problems solved by technology

However, the inventors herein have recognized potential issues with such an approach.

In one example, during an engine cold-start, when the temperature conditions of the engine are already not hot enough for an efficient combustion, advancing the injection timing responsive to an increase in fuel alcohol content may further cool the system and significantly reduce the efficiency of fuel evaporation and the formation of a homogeneous air-fuel mixture.

The larger amount of time required to evaporate the fuel may degrade engine startability.

Additionally, the charge cooling effect of the alcohol fuel on the intake system may further lower the air-charge temperature at cold-start conditions thereby further degrading combustion stability and increasing potential for engine misfire.

As such, this may lead to reduced fuel economy and degraded cold-start exhaust emissions.

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